In Japanese Patent Laid-Open Nos. 2000-96627 and 2001-41069, there is disclosed a construction machine having an auto-stop function for stopping an engine automatically upon establishment of preset auto-stop conditions (e.g., a state in which a gate lever for opening and closing a gateway for operator is opened and a lever for operating a working actuator is not operated).
However, in the construction machine having such an auto-stop function and with an air conditioner installed within a cab, since a compressor of the air conditioner is directly connected to the engine, the compressor becomes unable to be driven upon automatic stop of the engine and a cooling capacity of the air conditioner is eventually lost. Therefore, for example in the summer season, when the operator leaves the construction machine without turn-off of an ignition key and returns after a while, an interior of the cab may be no longer comfortable because of a rise in internal temperature, thus making it impossible for the operator to enter the cab and resume operation, with consequent deterioration of a working efficiency.